Question

In each of the following question, select the related number from the given alternatives.
$12$ $:$ $30$ $:$ $:$ $20$ $:$ $?$

• A. $48$
• B. $32$
• C. $35$
• D. $42$

Answer 1

The correct option is D $42$

$12=4^2-4$

$30=(4+2{)}^2-6=6^2-6$

Similarly,

$20=5^2-5$

$42=(5+2{)}^2-7=7^2-7$

Hence, D is the correct option.